Method for making stretch yarns and fabrics



1968 J. E. BROWN ETAL 3,

METHOD FOR MAKING STRETCH YARNS AND FABRICS Filed June 26, 1964 2 Sheets-Sheet 1 MULTI- PLY YARN COMPRISING AT LEAST 65% REGENERATED CELLULOSE HAVING A WET MODULUS =2 Ig/denAT 5%EXTENSION TREATING WITH EWELLING AGENT EQUIVALENT TO AQUEOUS SOLUTION CONTAINING 5 TO 40% NOOH AND ITO 8% NGCI IN THE ABSENCE BF TENSION,

COILED YARN REVERSE TWIST STRETCHY, BULKY, IRREGULAR YARN I 70 ven/ors James E Brown W/II/Um flan/r Ivy/0r By five/r afforneys wmdu-d m Jan- 1988 J. E. BROWN ETiAL fifi i' METHOD FOR MAKING STRETCH YARNS AND FABRICS Filed June 26, 1964 2 Sheets-Sheet 2 MULTI- PLY YARN COMPRISING AT LEAST 65% REGENERATED CELLULOSE AND HAVING AWETMODULUS OF Ig/den AT 5% EXTENSION TREATING WITH SWELLING AGENT EQUIVALENT TO AQUEOUS SULUTION CONTAINING 5 TO 40% NCIOH ANDI T0 8% NGCI IN THE ABSENCE OF TENSION CO1 LED YARN REVERSE TWIST STRETCHY, BULKY, IRREGULAR YARN PULL OUT E XTE NDED YARN WEAVINQKNITTING. ETC.

FABRIC RELAX WITH WATER OR STEAM STRETCH FABRIC F/GZ mvenfors James E Brown VIM/ram flan/r Toy/0r By their afiorneys United States 3,365,770 METHOD FOR MAKING STRETCH YARNS AND FABRICS James E. Brown, Axis, and William Frank Taylor, Mobile, Ala., msignors to Courtanlds North America Inc., New

York, N.Y;, a corporation of Alabama Filed June 26, 1964, Ser. No. 378,275 6 Claims. (Cl. 2876) This invention relates to a method for making stretch yarns and fabrics from cellulose filaments.

The use of stretchy yarns to make fabrics which have stretch properties has become increasingly widespread. Most of such yarns contain an elastomeric material, either as a component fiber or as an impregnant. The use of elastomers has drawbacks because in many instances they impart an undesirable hand or feel to the fabric and because they add to the cost of the fabric. Moreover, if stretch is imparted to the yarn before it is made into fabric, it becomes difiicult to handle the yarn on conventional textile machinery.

There is therefore a need for an inexpensive yarn which will have stretch properties, and which can be processed on conventional textile machinery.

In accordance with the present invention, such yarns are made by treating a multi-ply yarn comprising at least 65% by weight cellulose filaments having a wet modulus of less than 1 g./denier at extension with a swelling agent for cellulose equivalent in swelling elfect to an aqueous solution containing between about 5 and about 40% NaOl-l, and between about 1 and about 8% NaCl, said yam being treated in the substantial absence of tension, and then applying a reverse twist to the yarn.

Yarn made in accordance with the invention has an irregular appearance, as will be described more fully below. It may be drawn out and if retained in an extended position for a period of time, will lose its stretchy characteristics. In this condition it may be used on textile machinery like any non-stretch yarn, to make woven or knitted fabrics. Such fabrics upon being wetted out or steamed, without tension, will redevelop the stretch characteristics originally present in the yarn.

The invention therefore'further includes a method for making a stretch fabric which comprises treating a multiply yarn comprising at least 65% by weight of regenerated cellulose filaments having a wet modulus not greater than I g./denier at 5% extension, with a swelling agent for cellulose equivalent to an aqueous solution containing between about 5 and about 40% by weight NaOH, and between about 1 and about 8% by weight NaCl, in the substantial absence of tension, to form a coiled yarn, reverse twisting the coiled yarn, extending the coiled, reverse twisted yarn to pull out the coils, converting the pulled out yarn to a fabric and relaxing the fabric in an aqueous fluid to develop stretch.

in its product aspects, the invention comprises a multiply stretchy yarn comprising at least 65% regenerated ce lulose filaments having a wet modulus of less than 1 ./denier at 5% extension and having an irre ular three g g 3,365,770 Patented Jan. 30, 1968 ice Referring to FIG. 1, yarn in accordance with the invention is made by treating a multi-ply yarn comprising at least 65% regenerated cellulose fiber or filaments having a wet modulus of 1 g./denier or less at 5% extension with a swelling agent equivalent to an aqueous solution containing 5 to 40% NaOH and 1 to 8% NaCl, in the absence of tension.

There are currently available on the open market several different types of regenerated cellulose. Conventional textile grade viscose rayon is characterized by a crenulated surface and a distinct skin-core structure. It may have a conditioned tenacity of say 2.0 to 4 g./ denier and an elongation of say 14 to 30%. It is easily swollen in water and has a 'very low wet modulus, i.e., when wet a tension of not more than 1 g./dcnier is required to extend it 5%.

Another rayon currently available, though not ordinarily used in textiles, is the tire cord type. This, through the use of viscose modifiers, may have a smooth noncrenulated surface and no detectable skin-core structure. It may have a conditioned tenacity of 4-6 g./denier and an elongation of say 15 to 25%. Like conventional textile grade rayon, it too is easily swollen in water and has a wet modulus of less than 1 g./ denier at 5% elongation.

Recently a new class of rayon has appeared on the market, variously known as polynosique or high wet modulus rayon. In general it is made by spinning unripened viscose into a bath low in regenerative power and then stretching to a high degree. See Tachikawa, 2,732,- 279, and Cox 2,937,070. Such rayons may have conditioned tenacities as high as 7-8 g./denier with extensibilities below 10%. They are characterized by wet moduli of above 1 g./denier at 5% extension.

In our copending application Ser. No. 363,248, filed Apr. 28, 1964, we have disclosed a method for making stretch yarns and fabrics in which a multi-ply cellulose yarn containing at least 65% high wet modulus rayon is subjected, while relaxed, to a swelling agent equivalent to an aqueous solution containing 5 to 40% NaOH. As pointed out in that application, solutions of this nature may be applied to high wet modulus rayon without adverse afiect, but if applied to conventional rayon (or tire cord type rayon) they gelatinize it, breaking down the fiber structure. For this reason, cellulose fiber blends containing more than 35% textile grade rayon cannot be used with the process of my above copending application.

This is a substantial limitation on the use of the process described in said application since the cost of high wet modulus rayon is substantially higher than the cost of conventional rayon.

The present process meets this problem by employing a different class of swelling agents, namely those in which a modifying agent is employed to temper the action of the swelling agent. The preferred swelling agent for use in processes according to the present invention is an aqueous solution containing 5 to 40% NaQH and l to 8% NaCl. Equivalent solutions may, however, be made from various combinations of known cellulose swelling agents and salts. Thus, for example, the sodium hydroxide may be replaced by other alkali metal hydroxides and the sodiumchloride by other alkali metal salts of strong mineral acids; or alkali metal salts of organic acids having ionization constants (20 C.) of 1.50 or greater.

The multi-ply yarn used in the invention has at least two plies and may have up to say 6 plies. The individual filaments making up the singles yarns may be staple filaments, or continuous filaments.

Yarns employed in the present invention may also include a minor proportion of non-cellulosic fibers, provided however that such fibers do not affect the basic nature of the blend. 1

The singles yarns used in the plied yarn may be of any desired weight or construction varying from about 1 denier to about denier. They may be twisted in either direction: and to any desired extent. The twist in the component singles yarns, should, however, be opposite in direction to the ply twist. Normally the singles yarns will have 10 to 40 turns per inch and the ply 5 to 40 turns per inch in the opposite direction.

The temperature at which the swelling agent is applied may be varied considerably. In accordance with well known principles, lower temperatures tend to cause a more vigorous swelling action. Conveniently, the treatment is carried out at room temperature C, more or less) but may be carried out at any temperature between the freezing and boiling points of the solution.

The time of treatment will vary depending on the nature and concentration of the swelling agent and on the nature of the fiber, on the mechanical construction of the yarn and on mechanical details of the treating apparatus. Broadly, it may range from say 0.1 to 120 minutes.

The physical arrangements for treating the yarn may be any of those customarily used, provided that the yarn is maintained under substantially zero tension. The yarn may be passed through a bath of the swelling agent in the form of a catenary, or it may be laid down in a plaited pattern and passed through a bath, or sprayed, in that form. Alternatively, banks or skeins may be passed through a bath or sprayed.

Following contact with the swelling agent, the yarn is washed, neutralized with acetic acid or some other relatively weak acid, and dried. All of these steps are carried out with the yarn under substantially zero tension.

At this stage the yarn is as shown in FIG. 3. It is composed of a helical series of regular coils, the coils being substantially contiguous with one another and having a helix angle approaching 90 (say more than 45 In accordance with the invention, the yarn is now reverse 'twisted, i.e.. it is given a twist in a direction opposite to that in which it was plied. While the degree of reverse twist may vary, preferably it is between about 135 and 160% of the initial ply twist. The result is shown clearly and knitting machines,- precisely because it is stretch yarn.

However, this is not a problem with the present yarn because when the yarn is wound on a spool, preparatory to being converted into fabric, the tension incident to winding pulls the stretch out. If maintained under tension in the extended position for more than about 30 minutes, the yarn loses its recovery ability substantially entirely. Normally, the yarn stays wound on a spool for at least 24 hours before it is used and in this time the yarn loses its apparent stretchability. It can thus be woven or knitted just as though it had never had stretch characteristics. When, however, theresulting fabric is wetted, or steamed, under zero tension, the stretch characteristics redevelop and the result is a stretch fabric made of 100% cellulose. The steps required to make stretch fabric according to the invention are set out in FIG. 2.

The invention is illustrated in the following examples.

Example I A 30/2 yarn is spun from 1 /2 denier 1%" conventional All samples are rinsed in water for 3 minutes at 150 F. They are then neutralized in 5% acetic acid, rinsed and dried at 250 F. The resulting yarns vary considerably in their stretchability, the maximum stretch being obtained with solution F. 7

Example 11 A 24/2 yarn consisting of textile grade rayon having a wet modulus of about 0.3 g./denier at 5% elongation is treated, in the skein, in the absence of tension with an aqueous solution containing 20% NaOI-I and 5% NaCl at 20 C. for 2 minutes. It is then washed, rinsed, neutralized with acetic acid, rinsed and dried (relaxed) at C. The yarn is then reverse twisted 31.8 t.p.i. (148% of the ply twist). The yarn is wound into a skein and relaxed in water at 60 C. for 5 minutes, It is then extracted and dried, relaxed, at 120 C.

The yarn is then extended to,maximum stretch, held for 5 minutes, relaxed for thirty seconds and the growth determined as Percent growth length after stretching-length before stretching X 100 length after stretching From the growth, recovery is calculated as Percent recovery:

percent; elongation-percent growth x100 percent elongation where length at maximum st et h Percent elongation: length before stretching maximum stretch is found to be 167% with 59% recovery.

Example III erties by ravelling a strip one inch wide and twelve inches long. Reference marks are placed at the ten in'ch point.

The strip is then extended 25% and held for 5 minutes, relaxed for 5 minutes, again extended 25% and instantly relaxed. The recovery, calculated as above isfound to be 69%.

What is claimed is:

l. A method of making a stretchy yarn'which comprises contacting a multi-ply regenerated cellulose yarn at least 65% by weight of whose fibers have a wet modulus of not greater than 1 g./denier at 5% extension with a cellulose swelling agent equivalent to an aqueous solution of 5 to 40% sodium hydroxide and 1 to 8% NaCl, in the absence of tension, and then twisting the yarn in a direction opposite to its ply beyond the point where there is no twist in the original plied yarn.

2. The method claimed in claim 1 wherein the yarn is treated withan aqueous solution containing 5 to 40% NaOH at a temperature between about 0 and about 80 C. for between about 0.1 and about 120 minutes.

3. A method for making a stretch fabric which comprises treating a multi-ply yarn consisting essentially of cellulose filaments having a wet modulus not greater than 1 g./denier at 5% extension with a swelling agent [or cellulose equivalent to an aqueous solution containing between about 5 and about 40% NaOH and between about 1 and about 8% NaCl, at substantially zero tension, to form a coiled yarn, twisting the yarn in a direction opposite to its ply beyond the point where there is no twist in the original plied yarn, pulling out the coiled, reverse twisted yarn to form a substantially straight yarn, converting the straight yarn to a fabric and relaxing the fabric in an aqueous fluid.

4. The method claimed in claim 3 wherein the yarn is treated with an aqueous solution containing between about 5 and about NaOH, and between about 1 and about 8% NaCl, at a temperature between about 0 C. and about C. for between about 0.1 and about minutes.

5. A stretchy, multi-ply yarn produced according to the method of claim 1.

6. A stretch fabric produced according to the method of claim 3.

References (Cited UNITED STATES PATENTS 2,463,618 3/1949 Heberlein et a1. 57-157 JOHN PETRAKES, Primary Examiner. 

1. A METHOD OF MAKING A STRETCHY YARN WHICH COMPRISES CONTACTING A MULTI-PLY REGENERATED CELLULOSE YARN AT LEAST 65% BY WEIGHT OF WHOSE FIBERS HAVE A WET MODULUS OF NOT GREATER THAN 1 G./DENIER AT 5% EXTENSION WITH A CELLULOSE SWELLING AGENT EQUIVALENT TO AN AQUEOUS SOLUTION OF 5 TO 40% SODIUM HYDROXIDE AND 1 TO 8% NACL, IN THE ABSENCE OF TENSION, AND THEN TWISTING THE YARN IN A DIRECTTION OPPOSITE TO ITS PLY BEYOND THE POINT WHERE THERE IS NO TWIST IN THE ORIGINAL PLIED YARN.
 3. A METHOD FOR MAKING A STRETCH FABRIC WHICH COMPRISES TREATING A MULTI-PLY YARN CONSISTING ESSENTIALLY OF CELLULOSE FILAMENTS HAVING A WET MODULUS NOT GREATER THAN 1 G./DENIER AT 5% EXTENSION WITH A SWELLING AGENT FOR CELLULOSE EQUIVALENT TO AN AQUEOUS SOLUTION CONTAINING BETWEEN ABOUT 5 AND ABOUT 40% NAOH AND BETWEEN ABOUT 1 AND ABOUT 8% NACL, AT SUBSTANTIALLY ZERO TENSION, TO FORM A COILED YARN, TWISTING THE YARN IN A DIRECTION OPPOSITE TO ITS PLY BEYOND THE POINT WHERE THERE IS NOT TWIST IN THE ORIGINAL PLIED YARN, PULLING OUT THE COILED, REVERSE TWISTED YARN TO FORM A SUBSTANTIALLY STRAIGHT YARN, CONVERTING THE STRAIGHT YARN TO A FABRIC AND RELAXING THE FABRIC IN AN AQUEOUS FLUID. 